Pick 120‑150 grit for the first sweep, then switch to 180‑220 for a smooth, paint‑ready finish.
What Makes Drywall Sanding Different?
Joint compound is simply gypsum dust mixed with water and binders. Once dry it scuffs off with far less effort than wood, yet the cardboard face that surrounds each panel scars with little pressure. The job is a balance act: scrape ridges while keeping the paper intact, bring down tool lines while avoiding divots. That is why the right grit range matters so much. A 60‑ or 80‑grit sheet chews through mud yet leaves scratches that telegraph through primer. A 320‑grit sheet barely dulls knife streaks; between those extremes sits the drywall comfort zone.
Grit Numbers In A Nutshell
Abrasive grades follow an international scale. Lower figures mean larger particles and a faster bite. Higher figures pack smaller particles that polish. In wall finishing the working range lives between 80 and 220.
| Grit | Best Use | Why It Works |
|---|---|---|
| 80‑100 | Knocking down heavy ridges after taping | Swift removal rate, may scratch paper |
| 120‑150 | Main sanding between coats | Blends seams while guarding surface |
| 180‑220 | Final touch before primer | Levels nibs and feather edges |
Picking The Right Sandpaper Grit For Drywall Jobs
The first step is judging how much material stands proud of the field. If a knife edge catches on a ridge, start with 120. That grade removes material fast yet stays gentle enough for inexperienced hands. Family Handyman lists 120 to 150 as the go‑to range on most sites . USG echoes that guidance for its lightweight compound, naming 150‑paper or 220‑mesh as the sweet spot . Mesh sheets last longer because dust passes through the holes instead of clogging the face.
After knocking ridges down, glide a work light across the surface. Shadows tell the story. Tiny pits and raised flecks survive a coarse pass, so open a fresh 180 or even 220 sheet and float across the area with minimal pressure. This second stage erases scratches left by the coarser grit and feathers the joint compound into the paper.
Why 100 Grit Is Rarely The Starting Point
A hundred‑grit sheet seems like a safe bet, yet on fresh compound it can clog fast. Screens in the same number keep cutting longer, yet they still risk furrowing the paper if guided by an eager arm. Unless mud is applied thick, jumping straight to 120 speeds the cycle and limits damage. Fine Homebuilding calls 120 “the all‑around screen” and reserves 150 and finer for the closing pass .
Best Grit Range When Sanding Drywall Patches
Patching small dings or anchor holes places you one coat behind the original board texture. Start with a 180‑grit sanding sponge and buff the wet edge where the patch meets the paint film. The sponge flexes to hollow dips and rounds edges that a rigid block might miss. Many patch kits even include a fine sponge for that reason .
Large patches blended with several knives of mud call for a progressive plan. Begin with 120 on a pole sander, smooth the ridges, then lift to 150. Finish with 220 on a soft pad. That trio gives a flat surface with no swirl marks under an inspection light.
Mesh, Paper, Or Sponge: Does It Affect Grit Choice?
Grit number stays consistent across backing types, yet the cut feels different. Mesh acts like multiple tiny rasps, biting faster than closed‑coat paper of the same grade. Sponges remove less with each stroke, giving new painters more control. A quick field test tells the tale: If the surface turns white fast, lighten pressure or shift up a grit.
Step‑By‑Step Grit Progression
The table below shows a common path on new drywall. It maps a three‑coat finish, the style found in many homes and remodels.
| Stage | Grit Range | Goal |
|---|---|---|
| After second coat | 120‑150 | Blend seams, knock ridges |
| After third coat | 150‑180 | Feather edges, cut knife lines |
| Final skim (if used) | 180‑220 | Polish surface ready for primer |
Why You Might Skip 220
Some pros stop at 180 because primer with light filler properties hides micro scratches. If the finish color will be flat or eggshell, 180 often looks flawless. When walls take a semigloss or dark tone, move up to 220 to reduce light‑catching swirl marks.
Avoiding Common Sanding Mistakes
Using the correct grit solves half the battle. The rest comes from steady technique and dust control. Here are quick tactics seasoned crews follow:
- Keep the head flat. Tipping a pole sander digs trenches that even 220 cannot erase.
- Change sheets on time. Dull abrasive polishes instead of cutting, which tempts users to push harder and scar the surface.
- Light the surface. A raking LED flashlight shows ridges while standing dust hides them.
- Ventilate. Joint compound dust stays airborne for hours. Hook the pole sander to a vacuum when possible .
Wet Sanding And Grit Numbers
A damp sponge with a fine abrasive side replaces traditional sandpaper on small repairs. The texture falls around 220 grit. Wet sanding raises fewer particles yet leaves a slightly softer edge, so keep that in mind before priming .
The Role Of Dust‑Free Mesh
Vacuum‑ready heads paired with mesh sheets rated 150‑220 grit catch airborne debris at the source. USG’s Sheetrock line lists 220‑mesh as one of its preferred finishing options . Mesh also lasts longer because gypsum escapes through the holes.
When Coarser Than 100 Makes Sense
During gut renovations you may face old compound blobs or paint drips hard as rock. In those rare cases, start with 80 grit on a random orbit sander and a vacuum shroud. Once the bulk is gone, switch back to the normal drywall range to avoid scarring nearby paper.
Pro Tips For Longer Sheet Life
Abrasion wears edges first. Rotate the sheet on the hand block once the front corner dulls. With mesh, flip the pad to expose a fresh zone. Some contractors label each side with a marker so they rotate through all four quadrants before tossing.
Screen dust also shortens life. Tap the block on the floor or vacuum the sheet every few minutes. Screens cost more than paper yet maintain full cut after a quick clean, so the numbers even out over a room.
Choosing Between 150 And 180
This call often sparks debate. A 150 screen still removes slight tool chatter after the last coat while giving a milder scratch pattern than 120. An 180 sheet cuts slower yet leaves nearly no swirl. If timing matters and the crew primes the same day, 150 wins. If a homeowner plans to apply a sheen paint later, 180 earns its keep.
Grit And Primer Compatibility
Modern drywall primers fill scratches to a degree. Still, deep grooves can telegraph once the wall receives side light. Stick with 150 minimum, swing to 180 or 220 on accent colors.
Primer also seals paper fuzz revealed during sanding. If a spot looks furry after the first coat, lightly buff with a 220 sponge and touch up primer.
Safety Gear For Each Grit
Lower grit means heavier dust. Wear at least an N95 mask. Eye protection keeps falling grit out. A long sleeve shirt saves skin from fine shards. Vacuum‑supported tools lower airborne particles by half or more .
Backings And Their Ideal Grits
Sandpaper sheets: readily found up to 220. Use on hand blocks and smaller jobs.
Sanding screens: best between 120 and 220. Fit pole heads, resist clogging.
Sanding sponges: great between 150 and 220. Ideal for inside corners and details.
Inside Corners
Inside angles show scratches faster than fields. A fine sponge—around 220—flexes into the corner and touches both planes at once, blending without gouging. Lift out toward the flat, not into the angle, to avoid rounding the crisp line.
Trusted Brand Guidance
Product makers publish sanding charts. USG’s official FAQ calls for 150 paper or 220 mesh on its ultralight compound, matching the field wisdom gathered above.
Time‑Saving Sequence For DIY Painters
- Spot ridges with a scraping knife, slicing peaks instead of sanding them.
- Run a quick 120‑grit pass on seams.
- Sweep the room, vacuum, and shine a light.
- Glide a 180‑grit pole sander over everything in slow, even strokes.
- Touch inside corners with a fine sponge.
- Vacuum again, wipe walls with a damp cloth, then prime.
Frequently Overlooked Details
Old paint film. If you skim over satin or enamel, dull it with 150 prior to mudding for better grip .
Fastener bumps. Screw heads pulled too deep create volcanoes. Skim them, then hit with 150 on a block.
Texture matching. When blending knock‑down or orange‑peel, sand only the flat tops with 220, leaving dimples intact.
Matching Grit To Compound Type
Lightweight versions shed faster than all‑purpose mud, so they respond better to finer grades. Many crews jump straight to 150 on these mixes and finish with 220. On setting‑type powder compounds that dry harder, start with a 120 screen to open the surface, then move to 150. Fast‑setting fills often crown at the edges; skim them with a six‑inch knife while the mix is green to cut sanding time. Never attack a hard‑set ridge with coarse paper on bare drywall, as the paper gives way before the hump.
Additives such as glass bubbles inside lightweight blends reduce weight yet act like tiny beads under the abrasive. A worn 150 sheet can glide over those spheres and fail to cut. Swap sheets more often to stay sharp.
Reusable Versus Disposable Abrasives
Sanding screens and mesh discs stay productive four to five times longer than paper because dust escapes through the lattice. Rinse them under water, shake dry, and they feel almost fresh. Paper clogs in layers, and once the grit fills, the sheet only polishes. Yet paper costs less, tears to fit odd blocks, and wraps around corner sticks with ease.
Sponge pads fall between the two. They rinse clean like mesh yet the foam backing wears down after a few rooms. Keep sponges in labeled bins by grit so half‑used pads return to service on minor repairs. This habit keeps costs down while ensuring a sharp face is always ready.
Tool And Grit Pairings
Pole sanders work best with 120‑180 screens that resist loading and sweep large spans fast. Hand blocks pair well with 150 paper for spot work on nail pops and butt seams. Random orbit sanders fitted with a dust shroud tame rough patches when mastic or texture must vanish; run 80 or 100 discs first, then shift to 150 mesh for the blend pass. Corner sponges shine with 180‑220 faces that curve gently into angles without fraying tape.
Stick to that mix and you rarely hunt for a tool mid‑job. The right match saves minutes and spares shoulders from extra passes.
Store leftovers flat in a dry box; moisture dulls grit and causes rusty spots on mesh that scratch instead of cut.
Sharp sheets are money in the bank.
Truly always.